An investigation of protein syntheses during oogenesis and the preimplantation period of embryonic development will be undertaken. Particular emphasis will be placed on gene expression and control and on the synthesis of three classes of proteins: nuclear proteins (histones and non-histone chromosomal proteins), cell surface proteins, and mitochondrial proteins. Nuclear proteins and mitochondrial proteins will be analyzed at various developmental stages after radioactive labeling and cell fractionation. Cell surface protein will be either labeled endogeneously and isolated by precipitation with lectins or will be labeled by exogenous surface labeling techniques. With these studies as a foundation, three types of lethal mutations affecting preimplantation development will be analyzed. In each case, identical-twin "half embryos" will be prepared to permit definitive identification of the mutant homozygotes, and appropriate translocation chromosome markers will be used to facilitate identification. The mutations to be studied as three in the T-complex (t12, tw32, Thp) yellow (Ay), and oligosyndactyly (Os). The investigations of the T-locus mutants and Ay will emphasize surface proteins and metabolic regulation, as well as other aspects of protein and lipid synthesis. The study of Os will be directed toward an analysis of the synthesis and structure of tubulin and other microtubule proteins.